Technical Field
The present disclosure relates to a semiconductor device, a battery monitoring device, and a voltage detection method of a battery cell.
Related Art
As a technique for detecting a cell voltage of each of plural battery cells connected in series, the following technology is known. For example, in Japanese Patent Application Laid-Open (JP-A) No. 2001-56350, a voltage detection circuit for detecting voltages of an assembled battery including plural sample-and-hold circuits configured capable of holding a voltage of each unit battery between both electrodes of each capacitor, is described. In this voltage detection circuit, a capacitor group in which plural capacitors are connected in series is provided so as to corresponds to an assembled battery including plural unit batteries connected in series, and switches for sample-and-hold are provided at each of plural parallel lines. The plural parallel lines connect, between the assembled battery and the capacitor group, both electrodes of each unit battery and both electrodes of each capacitor that are arranged at the same order with each other. The voltage detection circuit includes a switch control means that simultaneously turns OFF the switches for sample-and-hold, and a voltage detection means detects a voltage between both electrodes of each capacitor by sequentially taking in a voltage between predetermined portions of the capacitor group when the switches for sample-and-hold are turned OFF.
However, in the voltage detection circuit described in JP-A No. 2001-56350, since the switches for sample-and-hold are connected to both electrodes of the capacitor, noise generated by operation of the sample-and-hold switches influences to the charges to be stored in the capacitor, and thus, accuracy of voltage detection of each unit battery (battery cell) may be decreased.
Recent years, in the battery monitoring devices, accuracy in detection of the cell voltage has been increasingly required, and decrease in accuracy of voltage detection as described above has become unacceptable.